The present invention is related to the field of data communications networks, and more particularly to data communications network management.
Network management encompasses a variety of activities with respect to communications networks, such as configuring, updating, monitoring and diagnosing network communications devices deployed within a network. In most instances the network communications devices, which are also referred to as “managed devices” herein, include hardware and software that supports these network management activities as well as an interface to a remote network management system of the managed network. While several such network management interfaces have been and continue to be used, one commonly used interface employs an open network management protocol known as the Simple Network Management Protocol (SNMP) along with a representation of network management data that conforms to an open specification known as the Structure of Management Information or SMI. Network management applications are deployed on a centralized network management system and engage in communications with the managed devices using the SNMP and SMI standards to carry out their network management tasks.
In particular, the SMI standards describe rules for writing abstract data collections referred to as Management Information Bases or MIBs. MIBs are specifications containing definitions of management information so that networked systems can be remotely monitored, configured, and controlled.
Although there are a wide variety of managed objects, for present purposes the focus is primarily on managed objects known as “interfaces”. In the context of data communications generally, “interface” refers to a logical relationship between two entities that operate at different hierarchical layers of a layered communications scheme. Typically, an “interface” refers to a communication layer beneath the network layer in the 7-layer OSI model. In the case of a point-to-point protocol (PPP) session being carried by an Ethernet VLAN, for example, involves a virtual interface layered atop a physical Ethernet interface.
In the context of SNMP and SMI, there is much content and structure pertaining to interfaces that are defined in a managed device. For example, a typical MIB includes an interfaces table that enumerates all the interfaces in a managed device and includes a variety of information about each of them, including such things as an interface type, a description, a speed, an address, administrative and operational status, counts of packets transferred and errors, etc. Additionally, the manner in which interfaces are identified in a MIB is itself the subject of standardization—there is an official list of interface “types” that have been assigned by the Internet Assigned Names Authority (IANA), and network management applications operate in part based on the use of standard interface types in MIBs.
Another pertinent type of managed object is an interface “stack”, which is a grouping of particular interfaces that together provide an interface between two entities that are separated in the hierarchical communications scheme. Continuing with the above example of a PPP session over an Ethernet VLAN, the virtual and physical interfaces are layered or “stacked” in that order.
It has been known to use a single data structure, referred to herein as an Interface Descriptor Block or IDB, to maintain various information pertaining to an “interface” as might be defined in a custom manner within a network communications device. Of particular pertinence here is the use of a single IDB by a software driver used in connection with an “interface” provided by a hardware interface module. A particular example might be a so-called “line card” for an optical communications link such as an Optical Carrier (OC)-x link, where x may have the value 8, 12, 48, etc. An internal interface provided by such a line card might be a single virtual tributary (VT) of a Synchronous Optical Network (SONET) connection, for example, and thus the “interface” may actually be a multi-layered interface including functionality at several hierarchical layers including a SONET Path layer and a SONET physical layer.